It is known, in a scrap-shredding plant, to use a mobile cover device for a shredder unit comprising a rotary drum able to rotate inside a shredding chamber.
The cover device is made substantially in a single body and is pivoted rotatably to the frame of the plant. The cover device is also provided with a plurality of separation means to separate and discharge the materials arriving from the shredding chamber. Here and hereafter in the description by separation means we mean those screens, centrifuges, aspirators, magnets or other similar or comparable devices able to selectively separate different types of materials. These materials are subsequently conveyed to suitable compartments and/or pipes present in the plant, expelled from the plant and sent to subsequent working steps or to storage.
The cover device in its normal operating condition covers the upper portion of the drum. When it is necessary to perform maintenance operations on said separation means or on the plant, the cover device is raised and made to rotate around its pivoting center following the activation of the actuation means associated with the cover device itself. One disadvantage of the known cover device is that, in the raised condition, it does not allow easy maintenance operations on the separation means and on the plant. In fact, the cover device, since it is substantially made in a single piece, does not allow easy inspection of the separation means located inside it, and therefore, if an obstruction occurs, partial or total, of said means, the operations to restore it are somewhat difficult. Moreover, lifting the cover device allows access with relative simplicity only to the upper part of the rotary drum, whereas access to the lower part of the drum, and to the shredding chamber, is somewhat inconvenient.
To solve this problem in the state of the art a connection means is provided, selectively able to be associated with the cover device in order to allow connection between the rotor shaft of the rotary drum and the cover device, so that the drum follows the cover when the latter is raised.
The connection devices comprise two housings disposed at the opposite ends of the rotary drum. Each housing is provided with a central hole inside which the rotor shaft of the rotary drum is able to be inserted, and with two lateral holes inside which attachment pins are able to be inserted in order to achieve attachment with the cover device. The centers of the lateral holes lie on a different plane from the plane on which the center of the central hole lies.
One disadvantage of these connection devices is that, when the attachment with the cover device is made and when the latter is in its raised condition, due to the above disposition of the holes, an imbalance of forces is caused which generates shearing stresses. Therefore it is necessary to provide structural reinforcements for the cover device so as to reduce the phenomena of wear and the risk of breakages deriving from said shearing stresses.
One purpose of the present invention is to achieve a cover device for a shredding plant which facilitates the maintenance operations.
Another purpose of the present invention is to achieve a cover device selectively able to be associated with the rotary drum by means of a connection device in which the phenomena of wear and the risk of breakages are reduced.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.